Abstract: A method and a system for the regulation of ventilation in a welding workshop, in which method the volume of supply air and/or extract air in the ventilation of the welding workshop is regulated. The basis of regulation of the volume is the load imposed on the electric power network by the welding equipment, e.g. the electric power consumed. The system comprises a set of measuring equipment for generating a measurement signal corresponding to the load imposed by the welding equipment on the electric power network. A set of control equipment has been arranged to regulate the volume of supply air brought into the welding workshop via a supply air duct and/or the volume of extract air removed from the welding workshop via an exhaust duct so as to achieve a level of ventilation proportional to the impurity load.